Has anyone tried TCP?

"Snip"

The proper name of the stuff is Tri-Cresyl Phosphate (spelling
questionable), a clear liquid, and you can get it from many FBO's. Aircraft
Spruce carries it and the required dispenser kit (listed in the Fuel
Additives section of their catalog). I usually buy it in quart (maybe
liter - I haven't checked) cans. Each can has a built-in insert that is
designed to interface with the dispenser syringe.

Not being a chemist, or an expert on internal combustion processes, I can't
talk about the actual in-cylinder mechanism - but here it is in layman terms
as I understand it: TCP mixed with the leaded fuel in very small
concentrations modifies the potential (metallic) lead deposits that are
freed from the leaded fuel during combustion, to a form (a soft compound)
that is readily blown out of a cylinder during the exhaust stroke.
"Snip"

Bill Bradburry